Electronic micrometer for sensing the diameter of a cylindrical body

ABSTRACT

A freestanding micrometer and method for determining the diameter of a cylindrical body, including measuring variations in diameter along a longitudinal length thereof, such as a roll used in the production of metal and paper sheet products. The micrometer comprises a housing supported on a circumferential surface of the cylindrical body. A first sensing element is movably supported by the housing and adapted for sensing a first surface point of the cylindrical body laterally spaced apart from the housing and disposed in a cross-sectional plane of the cylindrical body. A second sensing element is mounted to the housing for contact with a second surface point of the cylindrical body disposed in the cross-sectional plane of the cylindrical body. The first and second surface points locate, respectively, a terminal and midpoint of a chord lying in the cross-section plane of the cylindrical body, from which the diameter of the cylindrical body is determined.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/369,389, filed Apr. 3, 2002.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention generally relates to devices for measuringdimensions of a body. More particularly, this invention relates todevices for measuring the profile and/or diameter of a cylindrical body,such as a roll used in the production of sheet products.

2. Description of the Related Art

Cylindrical rolls used to roll sheet products, such as aluminum andpaper, are required to have a particular profile in order to obtain aflat rolled product. For this reason, the contours or profiles of suchrolls must be accurately measured and variations in diameters alongtheir lengths recorded. Freestanding saddle-type micrometers have beenwidely used for this purpose.

As represented in U.S. Pat. No. 5,088,207 to Betsill et al., afreestanding saddle micrometer generally includes a saddle supported onwheels for rolling (“skating”) along the longitudinal length of a roll.As used herein, the term “freestanding” is used in reference to asaddle-type micrometer in that such micrometers are not mounted to agrinder or other permanent apparatus, but instead are portable andplaced on the roll being evaluated. The Betsill et al. saddle micrometeris a caliper-type unit, in that the micrometer has oppositely-disposedarms that extend outward and downward from the saddle so as to belocated on opposite sides of a roll when the micrometer is placed on topof a roll. The arms are supported by a rocking crossbar. One of the armssupports a counterweight or follower probe, while the second arm carriesan indicator probe, such as a dial indicator or an LVDT (linear variabledifferential transducer). By locating the follower and indicator probeson their respective arms to be diametrically opposite each otherrelative to the roll, variations in the diameter of the roll can bedetected by skating the saddle along the length of the roll. If a dialindicator is used as the indicator probe, the saddle must make stopsalong the length of the roll to allow manual recording of the dialindicator reading. If an LVDT or other electronic transducer is used,variations in the roll diameter can be continuously recordedelectronically. The saddle is preferably equipped with an encoder tomeasure the distance skated along the length of the roll, and aminicomputer is mounted on the frame to read, record, and present inputdata from the LVDT and the encoder.

Existing saddle micrometers have several shortcomings that involvecompromises in weight, rigidity, balance and operation. In terms ofweight and rigidity, existing saddle micrometers have taken twoapproaches: either ignore weight for the sake of rigidity, which resultsin a unit that operators find difficult to handle but will, provideaccurate readings; or reduce weight to provide a unit that can be moreeasily handled, sacrificing rigidity to the extent that imprecisereadings may occur. This problem is exacerbated if electronic probes areused, since the unit is constantly in motion as readings are taken.Nonetheless, lighter-weight units have generally been more widelyaccepted because of the difficulty in handling the heavier, more rigidunits. Existing saddle micrometers are also generally top heavy, withthe result that the units are more prone to slip off the top of a roll.In the event of slipping off a roll, if a heavier unit is used the unitwill probably not be damaged but the operator is at risk of injury. Onthe other hand, if a lightweight unit slides off a roll, the unit ismuch more likely to be damaged.

Finally, from an operational standpoint, existing caliper-typemicrometers do not actually measure roll diameter, but instead arelimited to determining the profile of a roll, i.e., variations indiameter along the length of a roll. Furthermore, micrometers haverelied on an onboard minicomputer to acquire and process the collecteddata. Because of the limited computing power of these minicomputers,many electronic saddle micrometers are a simple unit that is easy tolearn and operate, but provides only basic profile information. Moreadvanced units are available that require extensive training to learnand skill to operate. While providing more detailed profile information,roll history and hard copy printout, in practice such enhancedcapabilities were rarely used because of the difficulty in learning howto operate the onboard minicomputer.

From the above, it can be seen that it would be desirable if a saddlemicrometer were available that overcame the shortcomings of the priorart, including improved rigidity, balance and operational featureswithout incurring excessive weight.

SUMMARY OF INVENTION

The present invention provides a freestanding micrometer and method fordetermining the diameter of a cylindrical body. The micrometer andmethod can be adapted to measure variations in diameter along alongitudinal length of a cylindrical body, such as a roll used in theproduction of metal and paper sheet products. The micrometer comprises ahousing and means for supporting the housing on a surface of thecylindrical body while the cylindrical body is oriented so that itslongitudinal axis is approximately horizontal. A first measurement meansis movably supported by the housing so that the position of the firstmeasurement means can be altered in a lateral direction that isapproximately perpendicular to the longitudinal axis of the cylindricalbody. The first measurement means is adapted for sensing a first surfacepoint of the cylindrical body laterally spaced apart from the housingand disposed in a cross-sectional plane of the cylindrical body. Themicrometer further comprises a second measurement means mounted to thehousing for contact with a second surface point of the cylindrical bodydisposed in the cross-sectional plane of the cylindrical body. The firstsurface point defines a terminal of a chord lying in the cross-sectionplane of the cylindrical body, while the second surface point defines alocation along the length of the chord. Finally, the micrometer isequipped with means for determining the diameter of the cylindrical bodybased on the length and height of the chord ascertained from first andsecond outputs of the first and second measurement means, respectively.

The freestanding micrometer described above makes possible a method ofdetermining the diameter of a cylindrical body withoutdiametrically-opposed sensing probes. According to the method, thehousing is placed on the surface of the cylindrical body while thecylindrical body is oriented so that its longitudinal axis isapproximately horizontal. The first measurement means is then positionedrelative to the housing in a lateral direction approximatelyperpendicular to the longitudinal axis of the cylindrical body, andproduces a first output signal by sensing a first surface point of thecylindrical body laterally spaced apart from the housing and disposed ina cross-sectional plane of the cylindrical body. A second output signalis produced with the second measurement means by sensing a secondsurface point of the cylindrical body adjacent the housing and disposedin the same cross-sectional plane of the cylindrical body as the firstsurface point. As such, the first and second surface points sensed bythe first and second measurement means define, respectively, a chordterminal and a point along the length of the chord, and the diameter ofthe cylindrical body is determined based on the length and height of thechord ascertained from the first and second output signals.

In view of the above, it can be seen that the freestanding micrometer ofthis invention structurally differs from freestanding caliper-typesaddle micrometers of the prior art by its capability to determine thediameter of a cylindrical body, instead of just the profile of the body.Furthermore, the micrometer is able to make use of a first sensingelement spaced apart from the housing by a single arm, and a secondsensing element carried close to or on the housing. Because of itscompact construction, the micrometer of this invention can beconstructed to be relatively lightweight, resulting in a unit that iseasier and safer to use. In addition, the micrometer of this inventioncan be constructed to be rigid relative to its weight, resulting in morereliable and precise data acquisition.

Other objects and advantages of this invention will be betterappreciated from the following detailed description.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 represents an electronic micrometer system placed on acylindrical body for sensing the diameter and diametrical variations ofthe body.

DETAILED DESCRIPTION

An electronic micrometer system 10 in accordance with an embodiment ofthis invention is shown in FIG. 1. The system 10 can be seen to comprisea portable unit 12 that includes a housing 14, an arm 16 extending fromthe housing 14, and a remote computer 28 such as a PC1. As seen in FIG.1, the housing 14 has a floor 20 and sidewalls 24 that generally definea rectangular-shaped box. The housing 14 may be constructed of aluminumor another relatively lightweight but rigid structural material. Thehousing 14 is capable of being very compact, for example, lateral andlongitudinal dimensions of about 6.75×8.25 inches (about 17×21 cm), witha weight of about eleven pounds (about 5 kg) or less.

The housing 14 is preferably equipped with four supports for supportingthe housing 14 on the upper arcuate surface of a cylindrical roll 40, asdepicted in FIG. 1. To enable the unit 12 to skate the roll 40 in orderto measure variations in the diameter (i.e., profile) of the roll 40along its length, the means of support are preferably wheels 30. Thewheels 30 are shown as being rotatably supported by bearings 34 so thatthe axis of rotation of each wheel 30 is substantially vertical whensupporting the housing 14, i.e., vertical to the floor 20 of the housing14. This orientation allows for the use of wheels 30 of small diameter,which more positively position the housing 14 on the upper surface ofthe roll 40 and therefore promote the accuracy of the unit 12. Asdepicted, the wheels 30 are sufficiently small so that their diametersare less than the diameters of the bearings 34 supporting them. Thehousing 14 is preferably equipped with an encoder (not shown) to measurethe distance traveled by the housing 14 via sensing rotation of one ofthe wheels 30. The housing 14, arm 16 and wheels 30 are preferablyconfigured to allow the unit 12 to be used for a wide range of rolldiameters.

The housing 14 is also shown as having a sensing element 22 mountedthereto for sensing the surface of the roll 40 beneath the housing 14.While shown as extending through the body of the housing 14, the sensingelement 22 could be mounted externally to the housing 14. Suitabledevices for the sensing element 22 include electronic linear measurementdevices, such as an LVDT, which generate an electronic signal thataccurately indicates displacement of a surface relative to the housing14. The sensing element 22 is preferably oriented to be aligned with aradius of the roll 40, e.g., vertical when the housing 14 is positionedtop-dead-center on the roll 40.

The arm 16 is shown as extending from one of the sidewalls 24 of thehousing 14, generally in a lateral and downward direction at an acuteangle to the floor 20 of the housing 14. The arm 16 includes graduations18 along its length, and a second sensing element 32 is adjustablymounted to the arm 16 with a bracket 26. As with the sensing element 22,a suitable device for the sensing element 32 mounted to the arm 16 is anLVDT or other electronic linear measurement device. The graduations 18on the arm 16 enable the sensing element 32 to be precisely positionedrelative to the housing 14, and therefore the sensing element 22. Asseen in FIG. 1, the sensing elements 22 and 32 are preferably orientedto be substantially parallel to each other, so that they come intocontact with surface points of the roll 40 as a result of beingdisplaced in parallel directions, e.g., vertical as shown in FIG. 1.Furthermore, the sensing elements 22 and 32 are not positioneddiametrically opposite each other relative to the roll 40. Asrepresented in FIG. 1, the sensing element 22 is located at or neartop-dead-center of the roll 40 while the sensing element 32 locates oneterminal of a horizontal chord “c” of the roll 40, represented in FIG. 1as the sum of two half-chords, each having a length of c/2. Because ofthe location of the sensing element 22 on the roll 40, the sensingelement 22 (and the surface point it locates) is vertically aligned withthe midpoint of the chord.

As evident from FIG. 1, the sensing elements 22 and 32 are adapted tomake contact with points on the surface of the roll 40 that arecircumferential spaced-apart, but lie in the same cross-sectional planeof the roll 40. The surface points contacted by the elements 22 and 32are geometrically related by the chord length, a vertical radius and asecond radius (r), which together define an angle as seen in FIG. 1. Aportion of the length of the vertical radius lies between the chord andthe surface point contacted by the sensing element 22, and is definedherein as the height (h) of the chord. Accordingly, the remainingportion of the vertical radius (between the chord and the longitudinalaxis of the roll 40) has a length r-h. Based on the geometricrelationship between the chord length (c) and chord height (h), thediameter of the roll 40 can be computed with the formula

d=(c ²+4h ²)/4h

where d is the diameter of the cylindrical body.

The chord height is able to be effectively measured with the sensingelements 22 and 32 as a result of the sensing elements 22 and 32 movingin a parallel direction to contact the surface points lying in the samecross-sectional plane of the roll 40. For this purpose, the two sensingelements 22 and 32 are calibrated relative to each other with regard totheir positions and measurement ranges. The chord length is twice thedistance c/2, and therefore twice the lateral (horizontal) distancebetween the sensing elements 22 and 32. For this purpose, the chordhalf-length is physically established by accurately positioning thesensing element 32 along the length of the arm 16 with the graduations18. The graduations 18 effectively serve as a chord scale that projectsout over a circumferential portion of the roll 40 adjacent the housing14. The graduations 18 define stops at which the movable sensing element32 can be located relative to the sensing element 22. As such, the unit12 is able to establish multiple chord lengths, such that a chord lengthcan be established that, based on the size of the roll 40 beingevaluated, will provide a measurable chord height sufficient toaccurately calculate the roll diameter, e.g., with an accuracy having arange of about 0.015 inch (about 0.4 mm) or less, without the need fordiametrically-opposed sensors. As depicted in FIG. 1, the accuracy ofthe unit 12 can be enhanced by including a temperature probe 36 forsensing the temperature of the roll 40 in the vicinity of the surfacemeasurements made by the sensing elements 22 and 32 to compensate forthermal expansion resulting from temperature variations.

In view of the above, it can be seen that the portable unit 12,comprising the housing 14 and arm 16, is capable of having a rigid,compact and relatively lightweight construction. The unit 12 thereforecan have a low profile and center of gravity, which equates to betterbalance when the unit 12 is in use, and therefore improved safety forthe unit 12 and its operator. The rigidity of the housing 14 promotesthe stiffness of the entire unit 12, such that the unit 12 has themechanical integrity to support state-of-the-art electronics. As theunit 12 skates the roll 40 in the direction of its longitudinal axis,there is minimal extraneous mechanical motion to distort the electronicreadings produced by the sensing elements 22 and 32.

The housing 14 is also capable of serving as an enclosure for dataacquisition hardware 38 and a suitable power supply, such as a battery(not shown). FIG. 1 schematically represents the micrometer system 10 asincluding the computer 28, which is separate from and outside thehousing 14. The computer 28 preferably utilizes dedicated software toprocess data stored by the data acquisition hardware 38 carried by thehousing 14, and is preferably capable of representing the data on ascreen 46. Any suitable communication device 48 can be used to connectthe computer 28 to the data acquisition hardware 38 for transferring thedata. In one embodiment, the device 48 is a cable, while in anotherembodiment the device 48 is a wireless module that allows data from theunit 12 to be transmitted to a remote location, such as where thecomputer 28 is a central terminal anywhere within the complex in whichthe measurements are being performed. According to another preferredaspect of the invention, the computer 28 is provided with touch screenicon-activated functions that are software-driven to receive and displaypertinent data quickly, simply, and in a user format. The touch-screencomputer 28 makes available to the operator an onscreen display of aroll profile skate, which can be projected over a target profile so theoperator can see if a roll is within specifications.

In view of the above, the electronic micrometer system 10 of thisinvention provides many capabilities and advantages lacking in prior artcaliper-type saddle micrometers. The portable unit 12 is able toaccurately measure the diameter of a cylindrical body without the use ofdiametrically-opposed probes, such that the unit 12 is relativelycompact and lightweight. In addition, the housing 14 provides a veryrigid, low profile unit with a low center of gravity, improving thebalance and handling of the portable unit 12. With the computing powerof the computer 28, the options for the manipulation and presentation ofdata become essentially unlimited. Total roll management, includingprofiling, evaluation, history and inventory, also becomes practicalwith this invention. The data acquired can be set for different levelsof access controlled by passwords (e.g., operator and management). Thestorage medium of the computer 28 can be readily sized to allow forindividual user requirements and subsequent system refinements andupgrades. Using a wireless module as the communication device 48, datafrom multiple units 12 can be transmitted to a central terminal, whererolls can be evaluated at the corporate, plant site, roll shop, operatorand/or grinder level. The inventory and life expectancy of rolls can bemonitored, and the history of each roll tracked from the day it is putinto service until the end of its useful life.

While the invention has been described in terms of particularembodiments, it is apparent that other forms could be adopted by oneskilled in the art. Accordingly, the scope of the invention is to belimited only by the following claims.

What is claimed is:
 1. An electronic profile acquisition micrometersystem for sensing the diameter and variations in the diameter of acylindrical body, the micrometer system comprising: a housing; means forsupporting the housing on a surface of the cylindrical body while thecylindrical body is oriented so that its longitudinal axis isapproximately horizontal; an arm mounted to the housing and projectingoutwardly therefrom in a lateral direction approximately perpendicularto the longitudinal axis of the cylindrical body; first measurementmeans movably mounted to the arm so that the position of the firstmeasurement means can be altered in a lateral direction approximatelyperpendicular to the longitudinal axis of the cylindrical body, thefirst measurement means being adapted for sensing a first surface pointof the cylindrical body laterally spaced apart from the housing anddisposed in a cross-sectional plane of the cylindrical body, the firstsurface point defining a terminal of a chord lying in the cross-sectionplane of the cylindrical body; second measurement means mounted to thehousing for contact with a second surface point of the cylindrical bodydisposed in the cross-sectional plane of the cylindrical body, thesecond surface point defining a location along the length of the chord;and means for determining the diameter of the cylindrical body based onthe length and height of the chord ascertained from first and secondoutputs of the first and second measurement means, respectively.
 2. Theelectronic profile acquisition micrometer system according to claim 1,wherein the housing is positioned on the cylindrical body while thecylindrical body is oriented so that the longitudinal axis of thecylindrical body is approximately horizontal, the second measurementmeans is positioned approximately top-dead-center on the cylindricalbody and the chord is horizontal so that the second surface pointlocates the midpoint of the length of the chord, the length of the chordbeing ascertained by the position in the lateral direction of the firstmeasurement means relative to the second measurement means.
 3. Theelectronic profile acquisition micrometer system according to claim 1,wherein the determining means is programmed to calculate the diameter ofthe cylindrical body based on the formula d=(c ²+4h ²)/4h where d is thediameter of the cylindrical body, c is the length of the chord, and h isthe height of the chord.
 4. The electronic profile acquisitionmicrometer system according to claim 1, wherein the determining meanscomprises: a computer outside the housing for calculating the diameterof the cylindrical body; and means for transmitting the first and secondoutputs to the computer.
 5. The electronic profile acquisitionmicrometer system according to claim 1, wherein the support meansenables the freestanding micrometer to travel along a longitudinallength of the cylindrical body.
 6. The electronic profile acquisitionmicrometer system according to claim 5, wherein the support meanscomprises wheels supported by bearings, the wheels having axes ofrotation oriented in a vertical direction when supporting the housing.7. The electronic profile acquisition micrometer system according toclaim 6, further comprising means for sensing a distance thefreestanding micrometer travels along the longitudinal length of thecylindrical body.
 8. The electronic profile acquisition micrometersystem according to claim 7, further comprising means for determining aprofile of the cylindrical body along the longitudinal length thereofbased on changes in the diameter of the cylindrical body determined atdifferent locations along the longitudinal length of the cylindricalbody.
 9. The electronic profile acquisition micrometer system accordingto claim 6, wherein the bearings having diameters larger than thediameters of the wheels.
 10. An electronic profile acquisitionmicrometer system for sensing the diameter and variations in thediameter of a cylindrical body while the cylindrical body is oriented sothat its longitudinal axis is approximately horizontal, the micrometersystem comprising: a portable freestanding micrometer unit comprising: ahousing; wheels mounted to the housing and adapted for supporting thehousing on an upper surface of the cylindrical body while thecylindrical body is oriented so that the longitudinal axis thereof isapproximately horizontal and the housing travels on the upper surface ofthe cylindrical body along a longitudinal length thereof; an arm mountedto the housing and projecting outwardly therefrom in a lateral directionapproximately perpendicular to the longitudinal axis of the cylindricalbody, the arm having graduations along a length thereof; firstelectronic linear measurement means for producing a first output signal,the first electronic linear measurement means being movably mounted tothe arm so that the first electronic linear measurement means can beselectively positioned along the length of the arm with the graduations,the first electronic linear measurement means being adapted forcontacting a first surface point of the cylindrical body when the firstelectronic linear measurement means is vertically displaced, the firstsurface point being laterally spaced apart from the housing and disposedin a cross-sectional plane of the cylindrical body, the first surfacepoint defining a terminal of a horizontal chord lying in thecross-section plane of the cylindrical body; and second electroniclinear measurement means for producing a second output signal, thesecond electronic linear measurement means being mounted to the housingfor contacting a second surface point of the cylindrical body beneaththe housing when the second electronic linear measurement means isvertically displaced, the second surface point being disposed in thecross-sectional plane of the cylindrical body and locating the midpointof the length of the horizontal chord; data acquisition means forreceiving the first and second output signals from the first and secondelectronic linear measurement means and storing the output signals asdata; a computer separate from and outside the housing for receiving thedata stored by the data acquisition means and calculating the diameterof the cylindrical body based on the length and height of the horizontalchord ascertained from the first and second output signals of the firstand second electronic linear measurement means, the length of thehorizontal chord being ascertained by the relative positions in thelateral direction of the first and second surface points sensed by thefirst and second electronic linear measurement means, the height of thehorizontal chord being ascertained by the relative vertical positions ofthe first and second surface points sensed by the first and secondelectronic linear measurement means; and means for connecting thecomputer to the data acquisition means for transmitting the data. 11.The electronic profile acquisition micrometer system according to claim10, wherein the computer is programmed to calculate the diameter of thecylindrical body based on the formula d=(c ²+4h ²)/4h where d is thediameter of the cylindrical body, c is the length of the horizontalchord, and h is the height of the horizontal chord.
 12. The electronicprofile acquisition micrometer system according to claim 10, wherein thewheels are supported by bearings and have axes of rotation oriented in avertical direction when supporting the housing.
 13. The electronicprofile acquisition micrometer system according to claim 10, furthercomprising means for sensing a distance the housing travels along thelongitudinal length of the cylindrical body.
 14. The electronic profileacquisition micrometer system according to claim 13, further comprisingmeans for determining a profile of the cylindrical body along thelongitudinal length thereof based on changes in the diameter of thecylindrical body continuously determined along the longitudinal lengthof the cylindrical body.
 15. The electronic profile acquisitionmicrometer system according to claim 10, further comprising means forsensing a temperature of the cylindrical body adjacent at least one ofthe first and second surface points.
 16. A method of determining thediameter of a cylindrical body, the method comprising the steps of:supporting a housing on a surface of the cylindrical body while thecylindrical body is oriented so that its longitudinal axis isapproximately horizontal; positioning a first measurement means relativeto the housing in a lateral direction approximately perpendicular to thelongitudinal axis of the cylindrical body; producing a first outputsignal with the first measurement means by sensing a first surface pointof the cylindrical body laterally spaced apart from the housing anddisposed in a cross-sectional plane of the cylindrical body, the firstsurface point defining a terminal of a chord lying in the cross-sectionplane of the cylindrical body; producing a second output signal with asecond measurement means by sensing a second surface point of thecylindrical body adjacent the housing and disposed in thecross-sectional plane of the cylindrical body, the second surface pointdefining a location along the length of the chord; determining thediameter of the cylindrical body based on the length and height of thechord ascertained from the first and second output signals; causing thehousing to travel along a longitudinal length of the cylindrical body;sensing a distance the housing travels along the longitudinal length ofthe cylindrical body; and determining a profile of the cylindrical bodyalong the longitudinal length thereof based on changes in the diameterof the cylindrical body determined at different locations along thelongitudinal length.
 17. The method according to claim 16, wherein thehousing is supported on an upper surface of the cylindrical body, thesecond measurement means is positioned approximately top-dead-center onthe cylindrical body and the chord is horizontal so that the secondsurface point locates the midpoint of the length of the chord, thelength of the chord is ascertained by the relative positions in thelateral direction of the first and second surface points sensed by thefirst and second measurement means, the height of the chord beingascertained by the relative vertical positions of the first and secondsurface points sensed by the first and second measurement means.
 18. Themethod according to claim 16, wherein the diameter is determined with acomputer program that calculates the diameter of the cylindrical bodybased on the formula d=(c ²+4h ²)/4h where d is the diameter of thecylindrical body, c is the length of the chord, and h is the height ofthe chord.
 19. The method according to claim 16, wherein the first andsecond output signals are transmitted from the housing to a computeroutside the housing, and the computer calculates the diameter of thecylindrical body.
 20. The method according to claim 16, furthercomprising the step of sensing a temperature of the cylindrical body.